The relative orientation of the fibula to the incisura of the tibia maintains ankle stability and plays an important role in force transmission to the talus.1 The most significant predictor of functional outcome after syndesmotic injury is anatomic reduction of the ankle syndesmosis and mortise.1–4
Gardner et al5 revealed that ankle syndesmosis malreduction after surgical fixation is common and may be as high as 52% on postoperative computed tomography scans. Off-axis clamp or implant placement is likely the major culprit in mal-reduction of the ankle syndes-moses.6–8
In a cadaveric study, syndesmotic suture button fixation results in less post-fixation displacement compared with screw fixation in the setting of off-axis clamping.7 Several other clinical studies have compared suspensory fixation with syndesmotic screws, often citing improved reduction with suspensory fixation techniques.9–11 Although it has been shown that syndesmotic malreduction may lead to worse functional outcomes, the threshold for acceptable malreduction is unknown.12 Therefore, the goal of surgery is to obtain an anatomic reduction.
Implants related to tubercle (Chaput or Volkmann) fixation or medial malleolus fixation may fall along the neutral anatomic axis and prevent ideal placement of trans-syndesmotic screws.
The following surgical technique describes how to improve a syndesmotic malreduction caused by interference between the syndesmotic screw placed along the neutral anatomic axis and previously placed tibial implants during ankle open reduction and internal fixation (ORIF) (Video).
Set up, Approach, Malleolar Fixation
Standard set up, approach, and malleolar fixation is completed based on the type of ankle fracture. The patient is supine with a bump under the operative hip for neutral rotation of the limb. The operative leg is elevated above the level of the contralateral leg to make lateral imaging easier to obtain. A thigh tourniquet is used. Based on the fracture patterns, an appropriate approach is completed. The fractures are exposed, reduced, and stabilized. Once the malleoli have been stabilized, the syndesmosis should be evaluated.
Initial Syndesmotic Fixation
Multiple reported methods are used to assess the syndesmosis; in the current cases, a dorsiflexion/external rotation stress test was used. This testing revealed persistent instability at the syndesmosis. The senior author's (S.R.Y.) preferred method for syndesmotic fixation uses 3.5-mm cortical screws that are placed approximately 1 to 4 cm above the joint with 4 cortices (when the appropriate length screw is available), but they will occasionally use only 3 cortices to avoid medial prominence.
In some cases, prior to screw placement, a ball spike reduction clamp is used to reduce the syndesmosis, avoiding excessive compression. The screws are then inserted along the neutral anatomic axis to avoid iatrogenic malreduction. Next, fluoroscopic views are obtained, including anteroposterior, mortise, and lateral.
The most important step to assess syndesmotic reduction is to obtain adequate imaging. There are several indicators of syndesmotic malreduction that must be carefully analyzed. Of particular importance is the lateral clear space (and its symmetry with the medial clear space), as well as the position of the talus relative to the tibial plafond. When recognized intraoperatively, syndesmotic malreduction must be addressed. In both of these cases, the fibula and talus were translated anteriorly relative to the distal tibia articular surface.
Correction of Malreduction With Suspensory Fixation
The first step to correct the malreduction is to remove the fixation and reassess the joint congruity. Once the syndesmotic screws are removed, the ankle joint reduces to an anatomic position, as was seen prior to syndesmotic screw insertion. If this does not happen, the malleolar fixation needs to be scrutinized.
It is possible that a malleolar malreduction is the cause of the syndesmotic malreduction. However, if the syndesmosis reduces once the syndesmotic fixation is removed, it can be assumed that the rigid screws caused the malreduction during insertion. The surgeon must confirm that the initial screw trajectory was appropriate.
In the cases presented, although drilling for the syndesmotic screws, the tibial implants were encountered, which directed the drill path—and to an even greater degree, the screw—away from the ideal trajectory. It is hypothesized that contact with these implants shifted the position of the screw and subsequently the fibula was malreduced within the incisura (translating the talus anteriorly).
At this point, the decision was made to use a less rigid fixation device, with the goal of attaining a stable anatomic syndesmotic reduction. An Ankle TightRope (Arthrex, Inc, Naples, Florida) was used. The hole from the inferior syndesmotic screw was used for the tightrope device, and an additional hole was not drilled. (Of note, the drill required for the Ankle TightRope system is 3.7 mm and the screw that was removed was a 3.5-mm cortical screw.) The device was then implanted based on the steps outlined in the technique guide.
Theoretically, the implants that interfered with the syndesmotic screw could interfere with the tightrope or cause attrition and failure over time. However, this outcome was not observed in either of the current cases. After implantation, fluoroscopy was used to re-evaluate the joint. The anteroposterior, mortise, and lateral images revealed an anatomic reduction. At this point, the syndesmosis was stressed again, and there was no instability noted.
Closure and Immobilization
The wounds were irrigated and closed in standard fashion. A short leg splint was applied and was left in place for 2 weeks until the first postoperative follow-up appointment. The patients were instructed to be non–weight bearing on the operative leg. At the first follow-up appointment, the sutures were removed and the patients were transitioned to a fixed ankle walker. Weight bearing was started at 8 weeks postoperatively.
A 60-year-old man with hypertension and hyperlipidemia presented with a right ankle fracture after a motor vehicle accident. The fracture pattern is most appropriately classified as an AO/OTA 44C1.2 fracture with a Chaput avulsion instead of an anteroinferior tibiofibular ligament injury (Figure 1). He had a fibula fracture above the level of the syndesmosis, a trans-verse medial malleolar fracture, and an anterior avulsion of the tibial origin of the anteroinferior tibiofibular ligament. Of note, there were multiple traumatic orthopedic injuries.
Case 1. Anteroposterior (A), mortise (B), and lateral (C) radiographs and a selected axial computed tomography scan (D) showing the Chaput fragment at the anterolateral tibia. The fracture pattern is most appropriately classified as an AO/OTA 44C1.2 fracture with a Chaput avulsion instead of an anteroinferior tibiofibular ligament injury.
His ankle fracture was reduced and splinted at presentation. He remained splinted until his ORIF 8 days later. During the operation, a one-third tubular plate was used to buttress the anterior tibia fracture. During drilling for the syndesmotic screw, the tibial implants were encountered. The syndesmosis was clamped at the time of drilling and the insertion of the syndesmotic screws. However, when the clamp was removed, malreduction with anterior translation of the talus was noted (Figure 2). It is thought that this was due to interference from the tibial implants with the rigid syndesmotic screw.
Case 1. Anteriposterior (A), mortise (B), and lateral (C) fluoroscopic views after syndesmotic screw placement showing concern for increased space in the superior joint (superior clear space) and asymmetry compared to the medial clear space, as well as anterior translation of the talus relative to the tibia.
As described above, the rigid screw was replaced with a suture button fixation device, which successfully provided stabilization without malreduction (Figure 3). Both screws needed to be removed to reduce the syndesmosis. The patient has most recently been seen approximately 1 year after this procedure (Figure 4). He was not noted to have any issues with the operative ankle. He had returned to his previous work as a farmer.
Case 1. The inferior screw path was used to place a suture button device and appropriate, stable alignment of the ankle is noted on anteroposterior (A), mortise (B), and lateral (C) fluoroscopic views. The malreduction caused by screw placement into the crowded tibia is improved by replacing the screws with a suture button device.
Case 1. The most recent postoperative anteroposterior (A), mortise (B), and lateral (C) radiographs reveal no loss of reduction and healed fractures.
A 67-year-old man with osteoporosis and osteoarthritis presented with an AO/OTA type 44B2.2 fracture (Lauge-Hansen supination external rotation type IV) after a fall off his bicycle (Figure 5). He underwent initial closed reduction and splinting followed by ORIF 5 days later.
Case 2. Anteroposterior (A), mortise (B), and lateral (C) radiographs showing an AO/OTA type 44B2.2 fracture (Lauge-Hansen supination external rotation type IV).
The fibula fracture was reduced and initially fixed with a lag screw. An 8-hole one-third tubular plate was then placed on the posterolateral aspect of the fibula. The medial malleolus was initially fixed with a tension band; however, this created some malreduction due to comminution at the fracture site. A buttress plate was added for stability and the 1 of the proximal screws was used as the anchor for the tension band.
After malleolar fixation, the syndemosis widened on external rotation stress, and a syndesmotic screw was placed. While drilling, the implants on the medial tibia were encountered, and a malreduction resulted during placement of the screw (Figure 6).
Case 2. Anteroposterior (A), mortise (B), and lateral (C) fluoroscopic views after syndesmotic screw placement showing concern for increased space in the superior joint (superior clear space) and asymmetry compared with the medial clear space, as well as anterior translation of the talus relative to the tibia.
As in Case 1, it is thought that the interaction between the screw and tibial implants caused the malreduction. The replacement of the rigid screw with a suture button device corrected the malreduction and provided stability to the syndesmosis (Figure 7). He was most recently seen more than 1 year after his surgery and was not noted to have any ongoing issues with his operative ankle (Figure 8).
Case 2. The screw path was used to place a suture button device and appropriate, stable alignment of the ankle is noted on anteroposterior (A), mortise (B), and lateral (C) fluoroscopic views. The malreduction caused by screw placement into the crowded tibia is improved by replacing the screws with a suture button device.
Case 2. The most recent postoperative anteroposterior (A), mortise (B), and lateral (C) radiographs reveal no loss of reduction and healed fractures.
Syndesmotic malreduction is a known complication of ankle fracture ORIF. Off-axis clamp placement or screw mal-positioning has been shown to lead to syndesmotic malreduction. It is thought that when the syndesmosis is reduced and rigidly fixed in place, it allows the ligaments to heal. In both cases presented in the current article, the syndesmosis was reduced but placement of a rigid syndesmotic screw caused a malreduction.
When drilling for the syndesmotic screw, tibial implants were encountered in both situations. It is thought that the screw trajectory was appropriate and that interference between the implants caused the malreduction. In both circumstances, the same trajectory was used for the suture button fixation and fluoroscopic imaging revealed improved alignment.
Careful preoperative planning is critical to the success of any case. When the need for syndesmotic fixation is anticipated, the surgeon may modify other implants to avoid the expected path of the syndesmotic fixation. Despite this precaution, the implant paths may interfere with one another. At that point, the decision has to be made which implants to change.
Off-axis syndesmotic fixation causes recognized problems, including the potential to cause malreduction and worse functional outcomes. However, there is risk to removing stable fixation on small peri-articular fragments because the surgeon may not be able to replace it and regain the anatomic reduction and stable fixation. It is in these cases that the present technique has clinical application.
In the presented cases, the syndesmotic screws were quad-ricortical. In theory, one could simply use a much shorter syndesmotic screw to stop short of the interfering tibial implants; however, it was thought that this would be inadequate fixation. The suture button was effective in these circumstances despite being in the same path as the screws because of the flexibility of the implant.
The replacement of a screw with a suture button device minimized ankle syndesmosis malreduction in the setting of implant interference. Figure 9 shows a side-by-side comparison for both described cases of the lateral views with syndesmotic screws (left images) and suture button device (right images).
Side-by-side comparison of the lateral views of case 1 (A, B) and case 2 (C, D) with syndesmotic screws (A, C) and suture button device (B, D) showing improvement of the malreduction with the suture button device.
The current authors often prefer to use screw fixation for syndesmosis reduction due to the greater cost of the suture button device compared with 3.5-mm cortical screw ($600 to $900 vs $30). The 2 cases presented are among hundreds of separate cases where the syndesmotic screw was sufficient in adequately reducing the syndesmosis without malreduction.
The malreduction caused by screw placement into the tibia with previous implants in these 2 cases is addressed by replacing the screws with a suture button device, which maintained appropriate, stable alignment of the ankle on subsequent fluoroscopic views. Thus, although the authors do not necessarily recommend routine use of a suture button device for syndesmosis fixation, these 2 clinical scenarios represent an indication for its use given the negative clinical impact of syndesmosis malreduction. Attention to syndesmotic malreduction should be taken after trans-syndesmotic screw placement and should be exchanged to a suture button device if needed.
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